West of Eden

West of Eden is a 1984 science fiction novel by Harry Harrison, followed by two sequels: Winter in Eden and Return to Eden.

Set in an Alternate History where dinosaurs never went extinct (outside of North America, where modern mammals and eventually humans evolved), the story centers around the conflict between humans and the Yilanè, a race of intelligent amphibious reptiles. The main character, Kerrick, is a human who was raised by Yilanè.

Tropes used in West of Eden include:

• Alternate Prehistory
• All There in the Manual: Some editions of the book carry a brief index of Yilanè bio-technology.
• Bizarre Alien Biology: Intelligent mosasaurs that reproduce like seahorses. Their bio-engineered tools are even more bizarre: living dart guns, microscopes that are actually highly modified frogs, squid and icthyosaur vehicles...
• Blue and Orange Morality: The Yilanè's Bizarre Alien Biology leads to them having a strange moral compass. For example, lying is impossible (and the concept never even occurs to them until Vaintè learns about it from Kerrick), and they are absolutely loyal to their communities to the point of dying upon exile; exiles who don't seize up and die are completely insane by Yilanè standards.
• Call A Dinosaur A Smeerp
• Cavemen: Co-existing with dinosaurs, but there's an in-story reason for this.
• Dating Catwoman
• Death by Sex: Male Yilanè will not survive being pregnant more than three times.
• Encyclopedia Exposita
• Fantastic Racism: Humans and Yilanè are not on speaking terms.
• Fictionary
• Guilt-Free Extermination War: Explored. The majority of Yilanè just see massacring ustuzou (humans) as pest control, and most humans return the favor. Vaintè at first considers useful ustuzou like Kerrick to be worth keeping around as tools (and later becomes psychotically obsessed with their destruction), but the Daughters of Life recognize ustuzou as sapient beings worthy of life and respect. Kerrick (after rejoining the humans) rejects the position that Yilanè are Exclusively Evil, and draws a demarcation between Yilanè who are killing humans and Yilanè who humanity can coexist with.
• Interspecies Romance: For, erm, a loose definition of "romance."
• Lady Land: The Yilanè—females control politics, science, and the military; males are artisans, poets and brood mares.
• Language of Truth: The nature of Yilanè language and thought processes makes them incapable of lying...until Vaintè discovers the concept after seeing Kerrick do it.
• Lizard Folk
• Living Ship: Yilanè sail the seas using genetically modified icthyosaurs with a compartment in their dorsal fin. They also have modified squid as smaller boats.
• Living Weapon: ...specifically a genetically modified lizard that shoots poisoned darts.
• Mister Seahorse: Yilanè reproduce in a similar manner to, you guessed it, seahorses.
• My Country, Right or Wrong: Hardwired into Yilanè biology. If a Yilanè is exiled from its city, its body shuts down. Some of them, however, are loyal to something other than their city, and their shutdown reflex will occur in response to different stimuli. The Yilanè are not quite sure how to cope with this.
• My Species Doth Protest Too Much: Enge, and the other Daughters Of Life.
• Organic Technology: Everything used in Yilanè society is a product of genetic engineering. Even the ancient Yilanè began by hunting using living crabs instead of stone tools, though one Yilanè scientist suggests that early on, the Yilanè did indeed use "artefacts."
• Punctuation Shaker: The Yilanè language, although the various typographical symbols are intended to represent specific sounds.
• Really Gets Around: The Paramutan are as frisky as bonobos.
• Reptiles Are Abhorrent: Although mammals ("ustuzou") are equally abhorrent to the Yilanè.
• Sliding Scale of Alternate History Plausibility: X-III or X-IV. Possibly a very loose III if you decide that the dinosaurs' survival isn't an ASB element.
• Somewhere a Paleontologist Is Crying
• Starfish Aliens: The Yilanè are somewhat humanoid in shape, but that's all that's humanoid about them.
• Starfish Language: A complicated combination of spoken words, positioning/gestures and color signals, described as so difficult that many Yilané never even get the hang of it.
• Stock Dinosaurs: Quite a few (complete with Yilanè names), but the Yilanè themselves are mosasaurs, not dinosaurs.
• Thunderbolt Iron
• Translation Convention